Design, development and applications of copper-catalyzed regioselective (4 + 2) annulations between diaryliodonium salts and alkynes

Intermolecular (4 + 2) cycloaddition with alkynes is a powerful approach to construct isocoumarin moieties, however, regioselectivity remains challenging for the transition metal-catalyzed approach. Here, the authors report copper-catalyzed regioselective (4 + 2) annulations between diaryliodonium salts and alkynes to synthesize isocoumarin-type natural products.